I just got colonization today and was messing around with it and found out that you can only get soldiers by assigning that role to a free colonist. That didn't seem to hard, but I cant figure out for the life of me how to do it. :( Any help appreachiated thanks.

In the colony screen click and drag your colonist to the Garrison panel and a list of professions will be displayed. If your colonist is outside the colony use the 'Change Profession' icon. For a normal game you will need to have 50 guns in stock to create a soldier or 50 guns + 50 horses for a dragoon.